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Power Steering pump questions

3091 Views 27 Replies 5 Participants Last post by  AaronJ
So I am in the planning phase of designing a crawler tractor for my dad and I to use for plowing/cultivating and snow plowing the driveway. Right now I am working on a parts list on what to get/use on this crawler. Kind of want to build it similar to dozerbuilder's Cat 22 that looks excellent. Anyway I am looking at using an older GM power steering pump from the mid 80s with the v-belt and remote reservoir but I am curious if it will be enough for what I am planning on using it for. I'm leaning on using a P/S pump because they are a lot cheaper to get brand new than going to say Northern Tool and buying a hydraulic pump ($185 vs $300).

For the blade I'm looking at using a hydraulic cylinder with a 1" bore and 6" or 8" stroke and for the 3 point hitch probably the same. Never done any work with hydraulics before so this is new territory for me, but I have read several threads on a similar subject (using a P/S pump). Would these P/S pumps be enough to run all of the hydraulics or should I look for something a bit larger that is generally much better suited for this type of application?
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The GM p/s pump will do fine with cylinders that size. It's not how many cylinders are being used, it's how many are being used at the same time.

A 1"x8" cylinder requires 6.28 cu-in of fluid. The normal 2"x4" GT lift cylinders require double that. A GM p/s pump delivers about 450 cu-in of fluid per minute.

It's going to be quick. I suggest a 2"x8" cylinder to keep the speed down to a reasonable 1.6 seconds for a full stroke.
So I would be looking for cylinders like this: Hydraulic Equipment, Grizzly Hydraulic Cylinder, Hydraulic Cylinder | Agri Suppl

Closest I could come up with from Northern Tool is a 2" bore and 10" stroke which I think would be way more than what I would need. Is there a way to make like a rubber stop to prevent the cylinder from lifting the blade or the 3 point hitch from going too far and doing damage?
There are metal stroke restrictors available. I'm not sure how long rubber would last. Anytime that something is repeatedly hammered with 2 tons of force delivered at 15 mph, there will eventually be damage.

Given a choice between a tie rod cylinder that's too long and a welded, cross tube cylinder that is the correct stroke length, I'll spend the extra money for the more compact package. Tie rod cylinders tend to be bulky in the first place, and space is usually at a premium on GT's.

The 6 and the 8 inch cylnders can be found here.
So this would be the better cylinder then for the blade and 3 point? 2x6x1.125 DA HYD CYL LION 20LH06-112 3000 PSI
Back in the 70's we made log splitters out of Ford power steering pumps, would braze up the relief valve, get bigger tank, we slow butter then a maul. Try Surplus Center for your hyd. needs, lot less money and the have brand names, my two cents.
So this would be the better cylinder then for the blade and 3 point? 2x6x1.125 DA HYD CYL LION 20LH06-112 3000 PSI
That one has a retracted length of 16.25", this one has a retracted length of 13", and this one has a retracted length of 14" and is priced in Canadian dollars. (Current exchange rate = 0.75959, or about US $79 will buy C $100 with the fees charged by the financial institution of your choice, if they are reasonable.)

Of note is the fact that a GM pump has a 25-50% higher pressure setting than most GT implement lift systems and those systems use 4" stroke cylinders which can lift up to 400 lb implements as much as 12" on a 3PH. It's all about the geometry.
Back in the 70's we made log splitters out of Ford power steering pumps, would braze up the relief valve, get bigger tank, we slow butter then a maul. Try Surplus Center for your hyd. needs, lot less money and the have brand names, my two cents.
I've been looking at both and yeah comparing the prices of the actual hydraulic pump to the GM pump seems like I can get the pump I really need and for cheaper than going for the GM P/S pump.
A used P/S pump at a salvage yard would not cost much more than 30 bucks around here...
Just lack of finding the right vintage is a challenge around me. But in all honesty I would much rather use newer parts or reman over used. Would like to get full worth out of it but it is an option just to even tie me over until I could get another. Looking at older threads for FEL on GT/LT one would need a pump between .31-.37? Just keeping my options open.
The pump should be sized to the tasks that it will be performing. FEL's require larger pumps because they need to move a pair of 1.5"- 2" bore cylinders with up to 18" of stroke length each in a reasonable amount of time. That is up to 113 cu-in of fluid in 5 seconds. A lift cylinder for a 3PH usually has a 2" bore and a stroke length of 4" requiring 12.6 cu-in of fluid in a second or two. Making fine adjustments as for a bulldozer blade is not going to happen with a FEL capable pump with less than a half second for a full cylinder stroke.

Apparently Chrysler switched to the Saginaw (GM) p/s pump several years ago. I stripped a '91 Dodge Caravan this summer that had the GM pump. There are relatively few p/s pump failures in cars and trucks. I'm currently driving an '89 Chev van with 220K miles on the clock that has the original pump. That's about 7000 hours of service and it is still doing its job. The number of GT's that attain that number of hours of service are few and far between. The norm is about 100 hours per year, or 70 years for 7000 hours.
Okay that makes me feel a whole lot better. I had briefly thought about turning this into a tracked FEL but I think the dozer and 3 point idea is much better.
I think for my final questions are, how large of a reservoir would I need? I'm thinking not much more than a 2 1/2 gallon (about 9.5 liters). What kind of hydraulic fluid should I use? And then what diameter of hose would be recommended as well as fittings?
The reservoir to support a pair of small implement lift cylinders only needs to be about 1-2 quarts. The reservoir for my FEL with 4 much larger cylinders is about 2 gallons.

Use quarter inch hoses and JIC 37° fittings. The fitting for the pump OUT port can be found at the bottom of this page. Of the 5 listed, I suggest one of the steel fittings.

The supply line from the reservoir to the pump should be larger than the pressure lines and specifically rated for suction lines. You really don't want that line to collapse. Barbed fittings and gear clamps are acceptable for the supply line. There may already be a fitting incorporated in the pump for the supply line which will dictate the size of hose required.

I use Dexron, but there are other fluids that will work as well, including power steering fluid, 10W30 motor oil, any of the hydro fluids from the various tractor manufacturers, or any quality hydraulic fluid. Pick one that is easily found on a weekend in a blizzard and doesn't cost an arm or a leg. Murphy rules!
Yeah I don't think Anodized Aluminum would last very long. Main reason I asked for what fluid to use was I'd rather just use the proper one that is safe for the cylinders and the pump. You know way more than I could ever, so i trust your judgement over my own. So with using zero turn hydraulic motors tied into to all of this 2 quarts or so will still be the max amount I would need all together?
Your zero turn hydros should have their own reservoir. If you intend to use the same reservoir for the auxiliary hydraulics, the only thing to concern yourself with is plumbing the auxiliary system in so as not to interfere with the hydro system. The hydro reservoir should have enough capacity for both systems as it sits, about 5-10 quarts.
Have a couple more stupid questions. Will that Saginaw pump work when its flat down? Originally I was going to use a Honda GX390 engine but with that being about 12-14hp or so and I'm also going to be running a GM 10SI alternator to run some extra stuff plus charge a larger battery. I know the alternator will be taking about 2-4hp or so from the engine to spin, plus with P/S pump running the hydros I wanted to go with a larger engine so I wouldn't be taxing a smaller engine. Looking at a vertical shaft Briggs and Stratton 500cc and 540cc Intek engines which are about 17.5-19hp (under ASE J134). The alternator I'm not worried about being pulley side down since its not running any fluid through it, I'm more worried about the P/S pump being pulley side down with it being sideways and running into issues.

Is this going to be a real concern? Should I look into a horizontal shaft engine again but larger than the GX390?

Then going back to what you had said before about setting up the hydo cylinders and motors in a way that they will not interfere with each other when I'm using both, how would I do that? Or is that at the control valves themselves when I plumb it all together?
There are no stupid questions, depending on your knowledge base. The jury's still out on some of the answers. :fing32:

Hydraulic pumps will work right side up, upside down, laying face down, or face up. It's all the same, as long as the shaft turns in the correct direction fast enough and there is a constant supply of fluid at their inlet.

The GM pump will require a bit over 2 hp, for the 2-3 seconds required to lift an implement. The rest of the time, it might need 1/4 hp to keep it running in a no-load state.

A 100 amp alternator will also require a bit over 2 hp at full output, and maybe as much as 1/4 hp with no load. I hooked an old '60's something 37 amp alternator to a bicycle many years ago for exercising. It is possible to generate enough electricity to power 3 car headlights (35 watts each) and a car radio for several seconds, even when you are out of shape. The 10 year old kids at the local public school could keep that pace for up to a minute. That's almost 0.15 hp, so 1/4 hp in a no-load state is very pessimistic.

The hydro and the auxiliary hydraulic pump should each have their own supply lines if using a common reservoir. Many hydros have an internal return system that cannot be tapped requiring that the auxiliary hydraulic system have a dedicated return line connected near mid level on the reservoir. There are some hydros that can be tapped for an auxiliary return. It depends on which hydro you have.

What hydro are we dealing with here? A fast look at the previous posts did not come up with that bit of data, unless my look was too fast.
I'm still trying to locate a either zero turn hydros or I'll be going with either 2 of these 7.20 cu in DYNAMIC BMER-1-125-WS-T4 WHEEL MOTOR

Or two of these Prince Heavy-Duty Hydraulic Motor — 12 GPM, 2200 PSI, Model# CMM50-4RP | Hydraulic Motors Mounting Brackets| Northern Tool + Equipment

I was looking for part #'s from older threads on here for surplus center on zero turn motor setups but they were several years old and they are no longer carried there.
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